System for ventilating and venting containers containing a fluid volume

ABSTRACT

A system for ventilating and venting containers containing a fluid volume, such as gearboxes containing an oil filling, with a line system which connects the container concerned to the atmosphere and, upon changes in the volumes located in the container due to temperature changes, permits pressure equalization, is characterized in that the line system contains a separating housing ( 12 ) in which a separating medium ( 46 ) having oleophobic and hydrophobic properties separates a first space ( 42 ), which is connected to the container, from a second space ( 44 ), which is connected to the atmosphere, and in that line connections ( 10, 14 ) to the separating housing ( 12 ) are laid in such a manner that liquid-phase substances deposited on the separating medium ( 46 ) can flow out of the first space ( 42 ) to the container and out of the second space ( 44 ) to the atmosphere.

The invention relates to a system for ventilating and venting containerscontaining a fluid volume, such as gearboxes containing an oil filling,with a line system which connects the pertinent container to theatmosphere and, upon changes in the volumes located in the container dueto temperature changes, enables pressure equalization.

Systems of this type are prior art. Containers which are located intechnical systems and which are filled with operating fluids, forexample, an oil-filled gearbox, above the oil surface contain a certainair volume which among other things is used for compensation of volumechanges of the oil filling which are caused by temperature changes. Theline system which leads from the container, for example, a gearbox, tothe atmosphere prevents pressure differences from building up that couldlead to leaks on the sealing system, for example, on housing passages.In systems which can be operated over a large temperature range, suchas, for example, is the case in gearboxes, where there is a largetemperature span between the cold start and the operating temperature,in operation considerable volumetric flows of air result within the linesystem for pressure equalization. In particular, there is the risk thata discharge of oil or oil condensate to the atmosphere with thevolumetric flow may occur or an entry of foreign materials from theatmosphere may take place.

With respect to this problem, the object of the invention is to makeavailable a ventilating and venting system which is characterized by anincreased amount of operating reliability with respect to preventing thedischarge of liquid phase substances and the entry of foreign substancefrom the atmosphere.

According to the invention, this object is achieved by a ventilating andventing system having the features specified in claim l in its entirety.

Accordingly, an important feature of the invention consists in that theline system contains a separating housing in which a separating mediumhaving oleophobic and hydrophobic properties separates a first spaceconnected to the container from a second space connected to theatmosphere, and that on the separating housing line connections are laidsuch that liquid phase substances which have been separated on theseparating medium can drain out of the first space to the container andout of the second space to the atmosphere. The oleophobic property ofthe separating medium prevents an overflow of oil to the atmosphere sidewithin the separating housing. At the same time, the hydrophobicproperty of the separating medium prevents the possibility of an entryof polar fluids, for example water, up to a material-specific pressuredifference from the vicinity, while pressure equalization is possible inthe form of the air volume without loading with liquid phase substancesfor a surface which is not completely wetted with liquid. The protectionoffered by the system according to the invention against ingress ofwater from the vicinity is especially important and advantageous whenthe system is used in containers of systems which are operated in a wetenvironment.

This is especially the case in containers such as gearboxes inautomotive engineering where during operation of the vehicles under wetconditions or cleaning of the vehicles in car washes or when washing byhand, the entry of water could be a concern if the protective actionoffered according to the invention were not present.

In especially advantageous exemplary embodiments, the separating mediumis formed by a filter medium which has oleophobic and hydrophobicproperties. In this way, the separating medium separates not only waterwhich may enter, but also offers protection against ingress of solidparticles. Especially, when used in automotive engineering, thisprevents road dust or other dirt particles from being able to travelinto the gearbox in operation.

Especially advantageously, the arrangement is made such that there is amount by means of which the separating housing can be fixed such that inits operating position it lies at a height which is above the container,and that the first space borders the underlying bottom of the separatinghousing on which the first line connection which leads to the containerdischarges. This ensures that liquid phase substances such as oil or oilcondensate from a pertinent gearbox which have been separated on theseparating medium can easily drain completely out of the first space bythe action of gravity.

In especially advantageous exemplary embodiments, the separating housingforms a hollow cylinder which surrounds the first and second space andwhose axis in the operating position runs horizontally, so that theunderlying region of the inner wall of the hollow cylinder forms thebottom which borders the first space and on which the first lineconnection discharges.

In this case, the arrangement can be advantageously made such that theseparating housing has one closed end and one open end which can beclosed by a housing cover and that the first line connection is locatedon the closed end on the radially outer edge of the hollow cylinder.

With respect to the structural configuration of the separating medium,the arrangement can be made such that a cartridge-like filter insert,which can be inserted from the open end of the separating housing, whichhas the filter medium which forms the separating medium and which in thefilter insert forms an inner cylinder which borders the second space andwhich is open on the end of the separating housing which can be closedby the housing cover. Due to the fluid connection of the second space tothe housing cover which has been formed in this way, the second lineconnection which leads to the atmosphere on the housing cover can bedirectly provided on this housing cover.

In this respect, the arrangement can advantageously be made such thatthe housing cover has a central cavity which is connected flush to theopen end of the inner cylinder which forms the second space in theclosed position which seals the separating housing, with the second lineconnection on the housing cover forming a drain channel which extendsaway from the cavity in the radial direction.

In especially advantageous exemplary embodiments, between the housingcover and separating housing, there is a connecting device by means ofwhich the housing cover can be fixed in the closed position such thatthe second line connection forms a drain channel which is pointeddownward for liquid phase substances from the cavity of the housingcover.

In especially advantageous exemplary embodiments, the connecting deviceis made in the form of a snap safety which has elastic retaining fingerson the housing cover and latch bodies which can be engaged to it bylatching on the separating housing, with guide parts which interact withthe retaining fingers on the separating housing for the closed positionof the housing cover dictating a rotary position with the underlyingsecond line connection. Thus liquid phase substances, for example,water, which has penetrated as far as the filter medium, can flow backagain to the atmosphere by the action of gravity.

In especially preferred exemplary embodiments, a bushing of elastomermaterial can be slipped onto the separating housing such that it forms asnap ring which keeps the retaining fingers latched, and the bushing canbe clipped with an annular groove located in its periphery to a carrierpart of the mount so that the bushing, in addition to its securingfunction, forms a flexible support of the separating housing.

The invention is detailed below using one exemplary embodiment which isshown in the drawings.

FIG. 1 shows a broken-away, schematically simplified perspective obliqueview of one part of a motor vehicle drive axle with a gearbox which isprovided with an exemplary embodiment of the ventilation and ventingsystem according to the invention;

FIG. 2 shows a perspective oblique view of the separately shownexemplary embodiment of the ventilation and venting system according tothe invention, shown enlarged compared to FIG. 1;

FIG. 3 shows an exploded perspective of only the separating housing ofthe exemplary embodiment, shown slightly reduced in size relative to thepractical exemplary embodiment, and

FIG. 4 shows a longitudinal section of the separating housing of theexemplary embodiment which is drawn enlarged about 1.5 times compared toa practical exemplary embodiment.

The invention is explained below using an example in which the containerwhich can be ventilated and vented by means of the system according tothe invention is the gearbox 2 of the drive axle 4 of a commercialvehicle, which axle is only partially and schematically suggested. Inthe manner which is conventional in these apparatus, the gearbox 2 isfilled with oil, above the oil surface there being a certain air volume.For pressure equalization over the entire operating temperature range ofthe drive axle 4 at a site on the gearbox 2 which is located at thehighest level in the normal installation position of the gearbox 2,there is a ventilation and venting connection 6. The latter is connectedto a first line connection 10 of a separating housing 12 via a firsthose line 8 which forms a first section of a line system. The separatinghousing has a second line connection 14 from which a hose line 16 whichforms a second section of a line system leads to the atmosphere. A mount18 which is screwed to the gearbox cover 20 fixes the separating housing12 in its operating position such that relative to the ventilating andventing connection 6 on the gearbox 2 it is located at a higher level sothat the hose line 8 forms a gradient section over which fluid drainagefrom the separating housing 12 to the gearbox 2 can take place by theaction of gravity.

FIG. 2 shows details of the mount 18 with a screw clip 22 for screwingto the housing cover 20 and a carrier part 24 which extends angledupward from the clip 22 and forms the actual support for the separatinghousing 12. The second hose line 16 which leads from the second lineconnection 14 of the separating housing 12 to the atmosphere extendsfrom the second line connection 14 a considerable distance downward asfar as the hose end 26, which is beveled. This facilitates that theflexible hose is able to elude, for example, the water jet of a washerwhen the pertinent associated vehicle is being cleaned. At a distancefrom the hose end 26, the hose line 16 is held by means of an elastichose support 28 which is clipped in a shoulder 30 which forms the lowerend of the mount 18.

FIGS. 3 and 4 show details of the separating housing 12. As is apparent,the separating housing 12, which is made substantially cylindrical,forms in the interior a hollow cylinder 32 with one closed end 34 andone open end 36. On the closed end 34, is the first line connection 10in a positional arrangement such that the inlet and drain channel 38into the hollow cylinder 32 discharges on its lowermost region in thenormal operating position. This region which is farthest underneath thelongitudinal axis 40 of the hollow cylinder 32 forms the first space 42which borders the inside wall of the hollow cylinder 32. This firstspace 42 is separated by the separating medium located in the separatinghousing 12 from the second space 44 which belongs to the atmosphereside.

In this example, the separating medium is formed by a filter medium 46which has oleophobic and hydrophobic properties and which is part of acartridge-like filter insert 48 which in the exploded drawing from FIG.3 is separately visible and can be inserted into the hollow cylinder 32from the open end 36 in the direction of the arrow 50. The filter medium46 forms an inner cylinder 74 within a support structure 52 which hasbeen injected molded from plastic with one closed end 54 and one openend 56, which with the filter insert 48 installed is flush with the openend 36 of the hollow cylinder 42. In the region of the open end 56, thesupport structure 52 is sealed by an O-ring 58 relative to the innerwall of the hollow cylinder 32. Within the hollow cylinder 32, the firstspace 42 and the second space 44 thus are completely separated from oneanother by means of the filter medium 46, which is used as theseparating medium in terms of an overflow of liquid phase substances inthe form of oil or oil condensate from the first line connection 10 orof water from the second line connection 14, while a volumetric flow ofair is enabled for pressure equalization between the spaces 42 and 44.

The support structure 52 has webs 60 which run lengthwise and webs 62which run crosswise, of which not all are visible in FIGS. 3 and 4 andwhich do not all have the same material cross section. Thus, in theinstallation position shown in FIG. 4, the web 60 at the top in FIG. 4has a larger material cross section and adjoins the inside of the hollowcylinder 32. Conversely, according to the drawing on the underlying,lower inner wall region of the hollow cylinder 32, there is not a stripwhich adjoins it and which runs lengthwise, so that between the filterinsert 48 with its altogether three support strips and the inner wall ofthe hollow cylinder 32, there is an open space which forms the firstspace 42. The spacer for preserving this open space is a button-likeprojection 64 which projects slightly radially on the strip 62 whichruns crosswise and which is not visible in FIGS. 3 and 4; the projectionadjoins the inner wall of the hollow cylinder 32 on the bottom of thefirst space 42 in the installation position shown in FIG. 4. When thefilter insert 48 and the separating housing 12 are joined, as issuggested in FIG. 3 by the motion arrow 50, the filter insert 48 isinserted in the corresponding position. This position is maintained inoperation since the O-ring 58 on the open end 56 of the supportstructure 42 with sealing pretensioning adjoins the inner wall of anedge depression 66 in the end section of the separating housing 12.

The separating housing 12 on the open end 36 can be closed by a housingcover 70 which is shown in FIG. 3. It has a central cavity 72 which, inthe closed position shown in FIG. 4, borders the open end 76 of theinner cylinder 74 which is formed by the filter medium 46 and containsthe second space 44. From the cavity 72 of the cover 70, which cavity isconnected to the second space 46, the second line connection 14 extendsin the radial direction downward. There is a connecting device in theform of a snap safety for attaching the cover 70 to the separatinghousing 12. For this purpose, on the cover 70, there are axiallyextending retaining fingers 78 and 80 which are peripherally distributedand which have openings 82 which, when the retaining fingers 78 and 80are slipped onto the cylinder jacket 84, latch to latching bodies 86. Toensure that the cover 70 can be moved into the closed position, i.e.,into a snap connection, only when the rotary position shown in FIGS. 3and 4 prevails, in which the second line connection 14 extendsvertically downward, on the separating housing 12 guide bodies 88 areformed between the latch bodies 86, which free distances of varied sizebetween themselves. Matched thereto, the retaining fingers 78 and 80have a different width so that the cover 70 and the separating housing12 can be moved together only in one desired rotary position such thatthe snap connection forms.

A bushing 92 of elastomer material, which is shown separately in FIG. 3and which is illustrated in FIG. 4 in the action position, in theslipped-on action position forms a snap ring which overlaps theretaining finger 78, 80 and ensures the latch engagement. The bushing 92has a peripheral annular groove 94 with which it can be clipped into asegment 96 on the carrier part 24 of the mount 18 so that the bushing 92in an additional function forms an elastic support of the separatinghousing 12.

For effective protection against ingress of dust or dirt particles fromthe atmosphere, the filter medium 46 can have a corresponding filterfineness. In this design of the filter medium 46, oleophobic andhydrophobic properties can be implemented with simultaneous permeabilityto a degree which is necessary for pressure equalization.

1. A system for ventilating and venting containers containing a fluidvolume, such as gearboxes (2) containing an oil filling, with a linesystem (8, 16) which connects the pertinent container to the atmosphereand, upon changes in the volumes located in the container due totemperature changes, enables pressure equalization, characterized inthat the line system (8, 16) contains a separating housing (12) in whicha separating medium (46) which has oleophobic and hydrophobic propertiesseparates a first space (42) connected to the container from a secondspace (44) connected to the atmosphere, and that on the separatinghousing (12), line connections (10, 14) are laid such that liquid phasesubstances which have been separated on the separating medium (46) candrain out of the first space (42) to the container and out of the secondspace (44) to the atmosphere.
 2. The system according to claim 1,characterized in that the separating medium is formed by a filter medium(46) which has oleophobic and hydrophobic properties.
 3. The systemaccording to claim 1, characterized in that there is a mount (18) bymeans of which the separating housing (12) can be fixed such that in itsoperating position it lies at a height which is above the container, andthat the first space (42) borders the underlying bottom of theseparating housing (12) on which the first line connection (10) whichleads to the container discharges.
 4. The system according to claim 1,characterized in that the separating housing (12) forms a hollowcylinder (32) which surrounds the first (42) and second (44) space andwhose axis (40) in the operating position runs horizontally so that theunderlying region of the inner wall of the hollow cylinder (32) formsthe bottom which borders the first space (42) and on which the firstline connection (10) discharges.
 5. The system according to claim 1,characterized in that the separating housing (12) has one closed end(34) and one open end (36) which can be closed by a housing cover (70)and that the first line connection (10) is located on the closed end(34) on the radially outer edge of the hollow cylinder (32).
 6. Thesystem according to claim 5, characterized in that a cartridge-likefilter insert (48) which can be inserted from the open end (36) of theseparating housing (12) has the filter medium (46) which in the filterinsert (48) forms an inner cylinder (74) which borders the second space(44) and which is open on the end (36) of the separating housing (12),which end can be closed by the housing cover (70).
 7. The systemaccording to claim 1, characterized in that the housing cover (70) has acentral cavity (72) which in the closed position which seals theseparating housing (12) is connected flush to the open end (76) of theinner cylinder (74) which forms the second space (44), and that thesecond line connection (14) on the housing cover (70) forms a drainchannel which extends out of the cavity (72) away in the radialdirection.
 8. The system according to claim 1, characterized in thatbetween the housing cover (70) and separating housing (12) there is aconnecting device by means of which the housing cover (70) can be fixedin the closed position such that the second line connection (14) ininteraction with the cavity (72) of the housing cover (70) forms thedrain channel which is pointed downward for substances, especially of aliquid phase.
 9. The system according to claim 1, characterized in thatthe connecting device is made in the form of a snap safety which haselastic retaining fingers (78, 80) on the housing cover (70) and a latchbody (86) which can be engaged to it by latching on the separatinghousing (12), and that guide parts (88) which interact with theretaining fingers (78, 80) on the separating housing (12) for the closedposition of the housing cover (70) dictate a rotary position with theunderlying second line connection (14).
 10. The system according toclaim 1, characterized in that a bushing (92) of elastomer material canbe slipped onto the separating housing (12) such that it forms a snapring which keeps the retaining fingers (78, 80) latched, and that thebushing (92) can be clipped with an annular groove (44) located in itsperiphery to a carrier part (24) of the mount (18) in order to form aflexible support of the separating housing (12).